1. Field of the Invention
The present invention relates to a wet electrophotographic image forming apparatus using a solvent. More particularly, the invention relates to an image forming apparatus which can appropriately manage replacement timing of consumables, an image quality management method and a storage medium recording a program executable of the method.
2. Description of the Related Art
Conventionally, an electrophotographic image forming apparatus forms an electric latent image on a photosensing body by means of laser or the like, develops the latent image using a toner, transfers a toner image to a medium to be transferred the toner image, such as a paper or the like, and then fixes the transferred image by heating and pressurizing for obtaining a printed product.
Also, as a wet type electrophotographic image forming apparatus employing an ink, the ink prepared by dispersing a toner particle in a solvent, solidifying the ink by removing the solvent in the ink. Such wet type electrophotographic image forming apparatus utilizes a property of solidifying ink to be transferred to a substance having higher affinity among substances. As means for removing the solvent from the ink, there is a technology for removing a residual solvent by a rotary absorbing body after squeezing off the solvent by a squeezing pressure of a squeezing roller provided at downstream side of a developing portion. In such case, in order to ensure recovery performance of the rotary absorbing body, the absorbed solvent is evaporated by heat. However, for environmental protection, the evaporated solvent is cooled, liquefied and collected. The residual solvent vapor left non-liquefied is discharged out of the image forming apparatus through a filter by means of an air pump.
In the conventional image forming apparatus, an activated charcoal or the like is used as a filter material. Since the filter may have a life time, it is required to be replaced regularly. Considering the filter as consumables, if a user does not replace the filter, collection performance for the evaporated solvent is inherently lowered to be discharged in increased concentration of solvent vapor. Discharge of high concentration solvent vapor should cause pollution in the environment.
On the other hand, concerning like time of the filter, it is frequently defined as a given period of use. However, since actual life time of the filter is significantly variable depending upon use frequency and use environment. Therefore, replacement cannot be performed at an appropriate timing to make environment protection and maintenance by the user unsatisfactory.
Furthermore, at the occurrence of lowering air flow amount due to blocking of the filter, failure of the air pump or any other reason, concentration of solvent vapor in the image forming apparatus becomes higher to potentially cause malfunction of various photosensors, lowering of an exposure laser amount and so forth to cause degradation of image quality and to cause fatigue of parts.
The present invention has been worked out in view of the drawbacks in the prior art as set forth above. It is therefore an object of the present invention to indicate replacement of filter due to influence of solvent used in the process of image formation whereby to cause degradation of image quality or fatigue of parts and to restrict discharged vapor concentration of collected solvent.
According to the first aspect of the present invention, a wet type electrophotographic image forming apparatus employing an ink containing a solvent, comprises:
a liquefying device for cooling the solvent evaporated during an image forming process and collecting liquefied solvent;
an air pump sucking left unliquefied by the liquefying device and maintaining in a vapor state;
a pressure sensor detecting a suction pressure of the air pump;
alarm means for comparing an absolute value of a pressure data generated by the pressure sensor and indicative of the suction pressure and a predetermined pressure range and generating an alarm when the absolute value of the pressure data is output of the pressure range.
In the preferred embodiment, the alarm means makes judgment of initial failure of a filter for absorbing and removing the solvent in vapor state or installation failure of the filter when the absolute value of the pressure data is greater than the pressure range, and makes judgment of fatigue of the filter or abnormality of the air pump when the absolute value of the pressure data is smaller than the pressure range.
On the other hand, the image forming apparatus may further comprises a concentration sensor provided in the vicinity of a rotary absorbing body for absorbing the solvent, for detecting a vapor concentration of solvent. In such case, the alarm means may compares a vapor concentration data generated by the concentration sensor with a predetermined vapor concentration range while the air pump is in operation normally, to make judgment of lacking of solvent supply when the vapor concentration is smaller than the vapor concentration range and to make judgment of fatigue of the filter when the vapor concentration data is greater than the vapor concentration range for alarming.
According to the second aspect of the present invention, an image quality management method in an image formation by means of a wet type electrophotographic image forming apparatus employing an ink containing a solvent, comprising:
a first step of preliminarily setting a pressure range of a suction pressure of an air pump which sucks the solvent in vapor state which is left unliquefied from a liquefying device which cools the solvent evaporated during an image forming process and collects liquefied solvent and maintained in a vapor state, by means of an air pump left; and
a second step of comparing an absolute value of a pressure data generated by a pressure sensor detecting a suction pressure of the air pump and indicative of the suction pressure and the predetermined pressure range and generating an alarm when the absolute value of the pressure data is output of the pressure range.
Preferably, in the second step, judgment of initial failure of a filter for absorbing and removing the solvent in vapor state or installation failure of the filter is made when the absolute value of the pressure data is greater than the pressure range, and judgment of fatigue of the filter or abnormality of the air pump is made when the absolute value of the pressure data is smaller than the pressure range.
Further preferably, in the first step, a vapor concentration range of the solvent in the vicinity of a rotary absorbing body which absorbs the solvent remained on a photosensitive belt as a photosensitive body is preliminarily determined, and in the second step, a vapor concentration data generated by detecting a vapor concentration of the solvent is compared with the predetermined vapor concentration range while the air pump is in operation normally, to make judgment of lacking of solvent supply when the vapor concentration is smaller than the vapor concentration range and to make judgment of fatigue of the filter when the vapor concentration data is greater than the vapor concentration range for alarming.
According to the third aspect of the invention, a storage medium storing a program for implementing an image quality management method as set forth above.